The present invention in its principal aspects involves an improvement of the invention disclosed in German patent No. 20 38 445 of June 15, 1978. In the German patent a gas generator for fuels consisting of coal of a fine grain size has been disclosed which is provided with a combustion chamber and a steam boiler arranged vertically above the combustion chamber. A combustion shaft leads from the combustion chamber to the boiler and is arranged with an excentricity relative to the vertical axis of the boiler. The boiler itself has a slanting bottom for entrained fly ash, slat, etc. The slanted bottom has a terminal discharge device for the fly ash, etc.
The combustion shaft extending to the boiler ends and opens up into the slanting bottom surface of the boiler. The boiler itself and likewise its slanting bottom surface and also the combustion shaft and likewise a discharge shaft leading from the combustion chamber are all provided with boiler pipes.
This structure is fairly complex and requires rather expensive wall construction for housing and forming the boiler pipes. It is in particular necessary to have a heat expansion compensator device in connection with the combustion shaft between the combustion chamber and the slanting bottom surface of the boiler. Preferably, this compensator device should be arranged at the point where the gas inlet pipe forming part of the combustion shaft and the gas outlet shaft from the combustion chamber which also is part of the combustion shaft are interconnected. For this purpose a heat resistant fiber material can be used. This, however, involves the risk of penetration of fly ash and this in turn may interfere with the proper operation of the compensator device.
The present invention therefore has the object to improve the structure of the combustion shaft which, as indicated, is composed of the gas inlet to the boiler and the gas exit from the combustion chamber. Such a shaft should be of a simpler construction which is less expensive and in particular the grooves formed by the boiler pipes within the combustion shaft should be avoided.